Re: [PATCH v2 16/20] nfs{,4}_lookup_validate(): use stable parent inode passed by caller

Jeff Layton
2025-01-17T14:05:27Z

On Thu, 2025-01-16 at 05:23 +0000, Al Viro wrote:
> we can't kill __nfs_lookup_revalidate() completely, but ->d_parent boilerplate
> in it is gone
>
> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
> ---
> fs/nfs/dir.c | 43 +++++++++++++------------------------------
> 1 file changed, 13 insertions(+), 30 deletions(-)
>
> diff --git a/fs/nfs/dir.c b/fs/nfs/dir.c
> index 9910d9796f4c..c28983ee75ca 100644
> --- a/fs/nfs/dir.c
> +++ b/fs/nfs/dir.c
> @@ -1732,8 +1732,8 @@ static int nfs_lookup_revalidate_dentry(struct inode *dir,
> * cached dentry and do a new lookup.
> */
> static int
> -nfs_do_lookup_revalidate(struct inode *dir, struct dentry *dentry,
> - unsigned int flags)
> +nfs_do_lookup_revalidate(struct inode *dir, const struct qstr *name,
> + struct dentry *dentry, unsigned int flags)
> {
> struct inode *inode;
> int error = 0;
> @@ -1785,39 +1785,26 @@ nfs_do_lookup_revalidate(struct inode *dir, struct dentry *dentry,
> }
>
> static int
> -__nfs_lookup_revalidate(struct dentry *dentry, unsigned int flags,
> - int (*reval)(struct inode *, struct dentry *, unsigned int))
> +__nfs_lookup_revalidate(struct dentry *dentry, unsigned int flags)
> {
> - struct dentry *parent;
> - struct inode *dir;
> - int ret;
> -
> if (flags & LOOKUP_RCU) {
> if (dentry->d_fsdata == NFS_FSDATA_BLOCKED)
> return -ECHILD;
> - parent = READ_ONCE(dentry->d_parent);
> - dir = d_inode_rcu(parent);
> - if (!dir)
> - return -ECHILD;
> - ret = reval(dir, dentry, flags);
> - if (parent != READ_ONCE(dentry->d_parent))
> - return -ECHILD;
> } else {
> /* Wait for unlink to complete - see unblock_revalidate() */
> wait_var_event(&dentry->d_fsdata,
> smp_load_acquire(&dentry->d_fsdata)
> != NFS_FSDATA_BLOCKED);
> - parent = dget_parent(dentry);
> - ret = reval(d_inode(parent), dentry, flags);
> - dput(parent);
> }
> - return ret;
> + return 0;
> }
>
> static int nfs_lookup_revalidate(struct inode *dir, const struct qstr *name,
> struct dentry *dentry, unsigned int flags)
> {
> - return __nfs_lookup_revalidate(dentry, flags, nfs_do_lookup_revalidate);
> + if (__nfs_lookup_revalidate(dentry, flags))
> + return -ECHILD;
> + return nfs_do_lookup_revalidate(dir, name, dentry, flags);
> }
>
> static void block_revalidate(struct dentry *dentry)
> @@ -2216,11 +2203,14 @@ int nfs_atomic_open(struct inode *dir, struct dentry *dentry,
> EXPORT_SYMBOL_GPL(nfs_atomic_open);
>
> static int
> -nfs4_do_lookup_revalidate(struct inode *dir, struct dentry *dentry,
> - unsigned int flags)
> +nfs4_lookup_revalidate(struct inode *dir, const struct qstr *name,
> + struct dentry *dentry, unsigned int flags)
> {
> struct inode *inode;
>
> + if (__nfs_lookup_revalidate(dentry, flags))
> + return -ECHILD;
> +
> trace_nfs_lookup_revalidate_enter(dir, dentry, flags);
>
> if (!(flags & LOOKUP_OPEN) || (flags & LOOKUP_DIRECTORY))
> @@ -2259,14 +2249,7 @@ nfs4_do_lookup_revalidate(struct inode *dir, struct dentry *dentry,
> return nfs_lookup_revalidate_dentry(dir, dentry, inode, flags);
>
> full_reval:
> - return nfs_do_lookup_revalidate(dir, dentry, flags);
> -}
> -
> -static int nfs4_lookup_revalidate(struct inode *dir, const struct qstr *name,
> - struct dentry *dentry, unsigned int flags)
> -{
> - return __nfs_lookup_revalidate(dentry, flags,
> - nfs4_do_lookup_revalidate);
> + return nfs_do_lookup_revalidate(dir, name, dentry, flags);
> }
>
> #endif /* CONFIG_NFSV4 */

Much nicer without the "reval" callback.

Reviewed-by: Jeff Layton <jlayton@kernel.org>